Household furnace stoker



March 20, 1934. R, l., LINDEMUTH HOUSEHOLD EURNCE STOKER V 3 Sheets-Sheet l Filed OCL. 9, 1951 March 20, 1934. R, LJNDEMUTHy HOUSEHOLD FURNACE STOKER Filed Oct. 9, 1931 3 Sheets-Sheet 2 I 0INVJENTLDR March 20, 1934.

R. L. LINDEMUTH HOUSEHOLD FURNAGE STOKER Filed Oct. 9, 1931 3 Sheets-Sheet 3 INVENTOR o u n n e a Patented Mar. 20, 1934 UNITED STATES PATENT OFFICE' 1,951,425 HOI'JSEHOLDFURNACE STOKER Ralph L. Lindemuth, Dormont, Pa.

Application october 9, 1931, sci-icl No. 551,832

1s claims. (01110-48) This invention relates to stokers, and in particular, to improvements in automatic stokers of the underfeed type especially adapted to domestic use with hot air or boiler furnaces in homes and small apartments where Slack bituminous coal is used as fuel.

One object of this invention is to provide an automatic Stoker of the underfeed type in which the volatiles and gases in the fuel will be libl0 erated before the fuel reaches the re bed of the Stoker and ignited before passage into -the combustion chamber.

Another object is to provide an automatic Stoker having means for breaking up the semicoke formations formed in the fuel as it moves upwardly towards the active re bed.

Another object is to provide an automatic Stoker having means for cutting and breaking up the ash and clinkers formed during the burning of low fusion fuel.

A further object is to provide an automatic Stoker for domestic use having oscillatinggrate bars in which means are provided for regulating the stroke of the bars and for changing the position of the bars.

A Still further object is to provide novel means for mounting the grate bars on the Stoker.

A still further object is to provide an automatic Stoker of the underfeed type which is rugged in construction, positive in operation and relatively cheap to manufacture.

These and other objects which will be readily apparent to those skilled in this particular art are accomplished by means of this invention, one

embodiment of which is illustrated in the accompanying drawings wherein:

Figure l iS a top plan view of my improved Stoker; f

Fig. 2 is a view in section taken on lines lI-II of Figure 1 and having the furnace pot shown in dotted lines to illustrate the relative position of the Stoker to the pot;

Fig. 3 is a view in section taken on lines III- III of Figure 1;

Fig. 4 is a view in side elevation of the Stoker;

Fig. 5 is a top plan view of the Stoker showing means for feeding fuel and air thereto;

Fig. 6 is a view in perspective of the ash breaking plate;

Fig. 'I is a View in perspective of a grate bar adjacent one side of the Stoker; y

Fig. 8 is a. view in perspective of the movable grate bars;

Fig. 9 is a view in perspective of the intermedi- 55 atc stationary grate bars;

Fig. 10 is a view in perspective showing the mounting of the grate bars;

Fig. 11 is a `viewin perspective of half of the fuel tuyre;

Fig. 12 is an enlarged view in detail showing the mechanism for changing the stroke of the movable grate bars;

Fig. 13 is a top plan View of the grate bar adjusting mechanism;

Fig. 14 is an enlarged view in detail of the cond5 nection between the fuel feed and the drive shaft, and

Fig. 15 is an enlarged view in side elevation of the damper regulating mechanism.

Referring to the drawings in detail, 10 indicates t@ the tapered pot of a hot air or boiler furnace of the type usually employed in heating houses or small apartments, having a Stoker 1'1 positioned therein for feeding low grade fuel such as slack bituminous coal to the combustion chamber of 21d the furnace.

The fuel to be fed into the furnace is placed in a hopper 12 which has a Screw shaft 13 passing therethrough for conveying the fuel to the Stoker 11.

The Screw conveyor 13 is connected to a shaft 14 which is driven by a `motor 15 through suitable gearing contained in a gear box 16. In order to prevent injury to the motor when the conveyor 13 becomes clogged or overloaded, a shear pin connection 17 is provided between the Screw shaft 13 1 and the shaft 14, which is adapted to break when the load on the screw conveyor exceeds a predetermined maximum. l

The screw conveyor 13 forces the fuel into a retort 18 located in the Stoker 11 below the active re bed. As the fuel is forced upwardly through the retort, the heat from the lire bed liberates the volatiles or gases and converts the fuel into e. semi-coke formation. The gases and volatiles are directed through the fire bed where they are ignited and pass to the combustion chamber. Jets of air forced through openings 19 in the face of a hollow tuyre 20 which is connected to an air chamber 21 in the body of the Stoker 11, are pro- 100 vided for supplying the volatiles and gases with air as they pass through the fuel bed.

The air chamber 21 is supplied with air through a conductor 22 leading from a forced draft fan 23 which is driven by the motor 15.

In order to break up the semi-coke formation and to prevent the fuel from matting at the top of the retort 18, a Series of cutting edges 24 are yprovided on the face of the air tuyre 20. The

, cutting edges 24 -cxtcnd into the fuel retort 1s 110 and the fuel is forced thereagainst by grate bars 25 which are slidably mounted on the top of the body of .the stoker and so arranged that they periodically move into and out of the fuel retort between the cutting edges 24 on the air tuyre. The ends of the grate bars 25 adjacent the fuel retort are sharpened as at 26 so that the coke formation will be effectively broken up and permit the fuel to be conveyed to the active fire bed which is supported on the sliding grate bars 25 and stationary bars 27.

' In order to protect the body of the stoker from being worn by the sliding bars 25, the stationary grate bars 27 are provided with transversely extending surfaces or flanges 28 on each end there- 28 on adjacent bars 27 coact to properly space the same and form bearing surfaces for the moving bars 25. To prevent the moving bars 25 from falling out of the grate, outwardly projectingy lugs 29 may be formed on each end thereof which are received in undercut portions 30 formed ln the ends of the stationary bars 27 above the surfaces 28. A member 31, which engages the surfaces 28 on one end of the bars 27, has its ends fastened to the body of the stoker 11 and securely locks the grate bars 27 in position on the stoker. In order to prevent matting in the fuel bed and to secure proper combustion the grate bars 25 and 27 are substantially of inverted U-shape in section and have openings 32 in the base thereof through which air is expelled into the nre bed from the air chamber 21. Also the bars 25 are so constructed as to be of less thickness throughout a' greater portion of the length and form slots 33 between the grate bars 25 and the bars 27. The air from the air chamber 21 is expelled through the openings 32 and slots 33 with sufficient force to prevent matting on the grate bars and in .sufficient quantities to insure proper combustion.

The bearing surfaces 28 on the ends of the stationary grate bars 27 are so shaped that when the bars 25 are moved into the retortl 18, the surfaces thereof will be somewhat lower than the level of the stationary bars and when moved in the opposite direction,'the bars 25 will be elevated so that the surfaces will be raised somewhat above the level of the stationary bars 27. Thus the bars 25 carry the fuel from the retort 18 and set it on lthe grate bars.

The bars 25 are periodically moved or oscillated into and out of the fuel retort 18 to break up the coke formation and feed the fuel into the re bed by a rocker bar 34 having a projection 35 thereon which engages the bifurcated ends of a lug 36 one of which depends from each of the bars 25. The rocker bar 34 is mounted in the body of the stoker 11 and has a crank arm 37 secured to one end thereof which is connected to a crank arm 38 on the end of a shaft 39 by a turnbuckle 40. The shaft 39 is mounted in bearings 41 and 42 carried by the screw conveyor 13 and-the gear box 15 respectively and is turned back and forth to oscillate the rocker bar 34 and agitate the grate bars 25.

To impart an oscillatory motion to the shaft 39 a U-shaped member 43 having a link 44 extending upwardly between the legs thereof is secured to the shaft 39. One end of the, link 44 is loosely mounted on the shaft 39 and the other is connected to a rod 45 which is screwed into a collar 46 surrounding an eccentric 47 mounted on the screw conveyor shaft 13.

From this arrangement it is readily apparent that as the screw conveyor 13 is turned, the ec- 1- centric 47 will impart a backward and forward movement to the rod 45 and the end of the link 44. The link 44 moving back and forth strikes the legs of the member 43 and causes theshaft 39 to be turned first in one direction and then in the other. In order to control the distance the shaft 39 will be turned in either direction so as to regulate the stroke of the bars 25, the legs of the member 43 -have set screws 48 extending therethrough which may be moved in or out of engagement with the .link 44. This adjustment permits the stroke of the bars 25 to be regulated in accordance with the coking qualities of the ffuel being supplied to the stoker.

It is also apparent that it may become necessary to change the position of the movable grate bars 25 on the stoker, as well as to change the length of the stroke of the bars when certain types of fuel are being burned in order to successively break up the coke formations in the retort 18, or the like. Such an adjustment may be readily obtained by lengthening or shortening the turn buckle 40 respectively, so as to increase or shorten the distance between the crank arms 37 and 38.

After the volatiles and gases in the fuel have been liberated, the fuel is moved into the fire bed by the moving grate bars 25 where the fixed carbon contained in the fuel is converted into heat. The grate bars 25 keep the active fire bed moving and as the fuel is burned the ashes resulting from combustion are conveyed into an ash chamber50 located at the heel end of the grate bars 25 and 27 and drop into an ash receiving receptacle (not shown) positioned in the bottom of the furnace.

In order to break up the clinkers and 1arger` pieces of ash formed during the burning of the fuel, an ash breaking plate 51 having a series of spaced sharp cutting edges 52 thereon, is positioned on the stoker so that the cutting edges extend into tlie ash chamber 50 and support the ash formation at the discharge end of the grate bars thereby effectively sealing the ash chamber and preventingl the air therein from travcling into the combustion chamber and diluting the gases of combustion. The cutting edges 52 are so formed on the ash breaking plate 51 that every other one` is shorter in length and positioned in the path of one of the moving grate bars 25. The ends 53 of the grate bars 25 are pointed and when moving into the ash chamber 50 coact with the cutting edges -52 on the ash breaking plate 51 to break up the lower part of the ash formation supported on said cutting edges 52 and effect a continuous discharge of a portion of ash formation.

In order to prevent any air 'leaking into the furnace through the ash chamber 50 and passing through the ash seal supported on the cutting edges 52 and traveling in a strata of incomplete combustion through the furnace, the ash breaking plate 50 is provided with an offset portion 54 which deflects the air leaking int the furnace and directs it through the fuel bed where it is used in the process of complete combustion.

In order to prevent the fire from burning out in the combustion chamber when the fuel feed has stopped due to the shutting down of the motor 15, dampers 56 and 57 are provided for closing the air conductor line 22 and an outlet stack 58 leading from the combustion chamber of the furnace. The dampers 56 and 57 are automatically operated by mechanism which is arranged to open the dampers when the motor 15 starts and to close the dampers when the motor stops.

The mechanism for controlling the dampers 56 and 57 comprises a centrifugal regulator 60 which is secured to the hub of a pulley wheel 61 mounted on the end of a shaft 62 leading into the gear box 16. The pulley wheel 61 is driven by the motor 15 through an endless belt 63. The regulator 60 has a collai` 64 on the outer end which is sldable on the shaft 62. The

collar 64 is grooved as at 65 in which arms 66 on the end of lever 67 are mounted. The lever 67 is centrally pivoted to a bracket 68 mounted` adjacent the furnace in any suitable manner and has chains or ropes 69 leading from the opposite end thereof which connect it with crank arms 70 and 71 on the dampers 56 and 57, respectively. From this arrangement it is apparent that when the motor starts, the collar 64 on the regulator 60 is pulled inwardly due to centrifugal force, which movement turns the lever 67 about its pivot and shortens the chains 69, causing the dampers 56 and 57 to be moved to their open position. When the motor stops, the collar 64 is moved outwardly on the shaft 62 and permits the dampers to be moved to their closed positions.

In order to remove ashes and the like which may fall through 'the slots 33 into the air chamber 21, a door is provided in the base of the stoker to permit access to the chamber.

While I have shown my improved Stoker to be of substantially rectangular shape and applied to a furnace having a roundor circular pot, it is understood that the body of the stoker may be of any desired shape and installed in any type of furnace, regardless of the shape thereof. When the stoker 11 is installed in a furnace, the spaces between the sides of the Stoker 11 and the pot 10 are closed by side plates 76, one edge of which is supported by the body of the Stoker while the other edge bears against the pot to which it conforms in shape.

It is readily apparent from the foregoing description that I have designed an automatic stoker of the underfeed type for use in furnaces of the type employed in heating houses and small apartments in which the volatiles and gases in the fuel are liberated before the fuel reaches the active fire bed and directed through the fire bed where they are ignited.

It is also apparent that I have designed an automatic stoker having agitating or oscillating grate bars which keep the fuel moving slowly from the fuel retort to the ash chamber and which are readily adjusted to permit the use of any type of bituminous coal, regardless of the coking qualities of the coal.

It is also understood that certain changes, modications and substitutions may be made in the stoker without departing from the spirit of my invention or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. A progressive feed stoker comprising a body having a fuel retort and a relatively narrow ash chamber at opposite ends thereof, grate bars spanning the space between said fuel retort and ash chamber, means for reciprocating some of said grate bars to move the ends thereof alternately into said retort and ash chamber respectively, whereby fuel is conveyed from the source to the ash chamber, cutting edges on the ends of said movable bars and transversely spaced projections extending into said ash chamber toward the discharge end of said grate bars, the lower portion of said projections coacting with the cutting edges on the movable grate bars on reciprocation thereof to positively break up the bottom of the ash formations in said ash chamber and effect a continuous ash discharge without disturbing the upper portion of the ash formation whereby an ash seal is maintained over said ash chamber.

2. An automatic stoker comprising a body having a fuel retort at one end thereof and a relatively narrow ash chamber at the opposite end, an air tuyre supported by said body, and having transversely spaced projections extending into said retort, an ash deflecting member on said body having transversely spaced projections extending into said ash chamber, grate bars mounted on said body and spanning the space between said retort and ash chamber, and means for reciprocating some of said grate bars to move the ends thereof alternately into the retort and ash chamber into coacting relation with the projections on said tuyre and ash deecting member respectively, to positively break up coke and clinker formations therein, the discharge ends of said reciprocating bars coacting with the lower part of the projections on said ash deilecting member to continuously break up and discharge the lower portion of the ash formation whereby sufiicient ash will be maintained on the projections to effectively seal the ash chamber.

3. In an automatic stoker having a fuel retort and an ash chamber, a grate comprising a series of spaced stationary bars, movable bars between said stationary bars, and having cutting edges on the ends thereof, means for oscillating the bars having the cutting edges so as to move the ends thereof into said retort and ash chamber, and means on the ends of said stationary bars for slidably supporting and elevating said movable bars above the level of the stationary bars when moving into said ash chamber for feeding fuel from said retort.

4. An automatic stoker comprising a body having a fuel retort and a relatively narrow ash chamber at opposite ends thereof, a series of grate bars spanning the space between said retort and ash chamber, transversely extending spacing fianges on the ends of said bars, movable bars mounted in the spaces between said firstmentioned bars and sldable on the flanged ends thereof, and means for reciprocating said movable bars, the flanges on said first-mentioned bars being shaped to elevate the movable bars when moved in one direction to feed fuel from said retort.

5. A grate for an automatic stoker comprising a series of spaced hollow stationary bars, a series of movable hollow bars, one of which is disposed in each of the spaces between said stationary ably mounted in each of the spaces between said stationary bars, transversely extending surfaces on the ends of each of said stationary bars for spacing the same and forming bearing surfaces for supporting the ends of said sliding bars, means operatively holdingl said sliding bars between said/ stationary bars, and means operatively actuating said slidable bars.

7. A grate for an automatic stoker comprising a series of stationarily mounted hollow bars, a series of hollow bars one of which is slidably mounted in each of the spaces between said stationary bars, transversely extending coacting surfaces on the ends of said stationary bars for properly spacing the same and forming bearing surfaces for supporting the ends of said sliding bars, undercut notches in the ends of said stationary bars, lugs on the ends of said sliding bars for cooperating with the undercut notches in said stationary bars for holding said sliding bars in said grate, and means `for actuating said slidably mounted bars.

8. An automatic stoker having a fuel retort and an ash chamber at opposite ends thereof, an ash breaking plate mounted on said body adjacent said ash chamber, a series of projections on said plate extending into said ash chamber, grate bars spanning the space between said retort and ash chamber, and means for reciprocating some of said bars to move the ends thereof alternately into said retort and ash chamber, respectively, the ends of said movable bars being adapted to coact with the projections on rsaid ash breaking plate to automatically crush clinker formations.

9. An automatic stoker of the character described comprising a body having an elongated fuel retort, an elongated ash chamber spaced therefrom and extending parallel thereto, an ash breaking plate on said body forming the outer wall of said ash chamber, a series of spaced pr/djections on said plate extending into said ash chamber, a seriesof spaced stationary grate bars mounted on adjacent walls of said fuel retort and ash chamber and spanning the space therebetween, transversely extending spacing members on the ends of each of said bars the said spacing members of adjacent bars coacting to form bearing surfaces therebetween, movable bars slidably supported on said transverse surfaces, and means for oscillating said movable bars, the ends of said movable bars being arranged to move intermediate the projections on said ash breaking plate to automatically break up clinker and ash formations.

10. An automatic stoker of the character described comprising a body having a fuel retort at one end and an ash chamber at the opposite end thereof, cutting projections exten-ding into said fuel retort, cutting projections extending into said ash chamber, stationary grate barsmounted on said body and spanning the space between said retort and ash chamber, transversely extending spacing flanges on the ends of said bars, movable bars slidably supported on said spacing flanges, and means for oscillating said movable bars to cause the ends thereof to move alternately into the fuel retort and ash chamber and cooperate with the cutting projections on the retort and ash chamber, respectively to automatically break up coke and clinker formations.

11. A continuous ash discharge and crushing means for a progressive feed stoker having reciprocating grate bars comprising means extending transversely of the discharge end of said grate bars and coacting therewith to form a relatively narrow ash chamber, said means including transash formation and effect a continuous ash dis'- charge.

12. In combination with a progressive feed stoker having reciprocating grate bars, of means for providing an ash seal and a continuous ash disposal at the discharge end of said stoker including means at the discharge end of said grate bars and coacting therewith to form a relatively narrow ash chamber, and means extending into said ash chamber towards the end of said grate bars for supporting the ash formation and sealing the ash chamber while coacting with the grate bars upon reciprocation thereof to positively break and continuously discharge the lower part of the ash formation.

13. In combination with a progressive feed stoker-I having reciprocating grate bars, of means for sealing the discharge end of the stoker and for continually breaking up and discharging the ash formation, comprising means coacting'with the discharge end of the grate bars to forma relatively narrow ash chamber, means for directing the ash' formation into said ash chamber, andv means in said ash chamber and projecting toward the discharge end of said grate bars for supporting the ash formation to effect a seal of said ash chamber, said last-mentioned means coacting with the ends of the grate bars upon reciprocation thereof to positively break up and continuously discharge the lower portion of the ash formation supported thereon.

14. In combination with a progressive feed Stoker having a reciprocating grate and a relatively narrow ash chamber at the discharge end of said grate, of means for providing an ash seal 110 for said chamber and continually breaking 1p and discharging a portion of the ash therein,- comprising transversely spaced projections extending into said ash chamber for supporting the ash formation thereon, and means for directing 115 the ash formation onto said projections, the discharge ends of the grate upon reciprocation thereof coacting with said projections to break up the lower portion of the ash formation to continuallydischarge a portion of the ashes from said stoker. l

15. In a progressive feed stoker of the type having a feeding means and a reciprocating grate forming the burning area for conveying the fuel from the feeding means to an ash receiver, of

means for positively breaking up the ash formation and for maintaining an ash seal at the discharge end of the grate without the use of crushing rollers and dead end plates including, spaced projections extending a substantial distance into said ash receiver toward the discharge end of the grate for receiving and supporting the ash formation and coacting with the discharge end of the grate upon reciprocation thereof, to positively break up the lower portion of the ash formation supported thereon to provide a continuous ash discharge.

16. In combination with a progressive feed Stoker having a reciprocating grate, of means for providing an ash seal and a continuous ash disposal at the discharge end of said stoker, including means at the discharge end of said grate and coacting therewith to form a relatively narrow ash chamber, and means in said ash chamber for supporting the ash formation to seal the versely spaced projections extending toward the cash chamber while coacting with the grate upon discharge end of the grate bars adapted to support ash formations thereon and effectively seal the ash chamber and to coact with the grate bars reciprocation thereof to effect a continuous discharge of thelower part of the ash formation. 17. In combination with a progressive feed upon reciprocation thereof to positively break the stoker having a reciprocating grate, of means for receiving the discharge end of the stoker and for continuously breaking up and discharging the ash formation, comprising means coacting with the discharge end ofthe grate to form a relatively narrow chamber therebetween, means for direct.- ing the ash formation into said ash chamber, and means for supporting the ash formation to effect a seal of said ash chamber, said last-mentioned means coacting with the ends of the grate upon reciprocation thereof to progressively break up and continuously discharge the lower portion of the ash formation supported thereon.

18. In combination with a progressive feed stoker having a recprocableE grate, of a member extending transversely of the discharge end of Patent No. l, 951, 425.

'RALPH L. LINDEMUTH. r

the grate and coacting therewith to forma relatively narrow ash 'chamber therebetween, and means for reciprocating said grate to move the discharge end thereof alternately into and 'out of said ash chamber to vary the width of the chamber and to position a column of ash thereover, the discharge end of the grate when moving into said chamber coacting with the lower part of said member to crush and continuously discharge the bottom of said ash column and conveying ash to said chamber to continuously replace the top of the column and maintain an ash seal over said chamber.

RALPH L. LINDEMUTH.

r C'ERTIFIQAT 0F- coRREc'tloN'l March 20, 1934.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: 'Page 3, l line 136, claim -5. for "and means" read transversely extending coacting flanges; a'nd that the said Letters Patentl should be -read with this correction therein that the same may conform to the record of the ense in the Patent Office.

Signed and sealed this 15th day of May, A. D. 1934.

(Seal) Bryan M. Battey Acting Commissioner of Patents. 

